so over a wide range 0f 25c-70c we are off by at most 0.116?
The temperature dependent pH shift that we are talking about here is dependent on the solution and is likely different between the buffer solutions mentioned in above statement and mash or wort. This is why we can’t compensate for them universally. Aside from the fact that they are actual changes in pH.
Kai
Also keep in mind that there is temperature compensation because of the difference in the electrical signal at different temps, and then theres temp changes in the solution that Kai is referring to. When your meter has ATC (auto temp comp) it is only adjusting the readout based on temp. Its not converting your reading to what it is at 68F.
yes, but if the meter can handle the temperature with good repeatability, an individual could make a small correlation table between mash temp ph and at room temperature ph.
I don’t think so, because it depends on the composition of the solution. I assume it’s also related to water chemistry and wort gravity.
Well, to be fair, the pH range of enzyme activity is measured at the temperature they are active, meaning they’re measured at mash pH. So we are making this correction when we measure wort pH at room temperature.
I too think that the pH over temp curve will be fairly similar between wort samples.
Kai
I realize that ideal mash conditions are in the 5.2-5.7 range, but what is the real difference of a mash conducted at 5.2 vs. 5.6 in terms of beer flavor. This would be a great experiment. How does this effect mash efficiency or beer flavor. I think Kai has conducted some experiments in this regard. I’ve made excellent beers at both ends of the pH spectrum. Tannin extraction increases with increasing pH, but what can be said for a mash conducted on he higher side of the range?
This is an interesting mechanism that isn’t clearly understood in terms of it’s effect on the end product. I would like to see some further experimentation on the effects of mash pH on beer flavor.
While we’re discussing pH, why is the final pH of wheaqt beer so much loer than all-barley beer in spite of both starting at a similar mash pH?
The more aggressive fermentation leads to a faster and larger pH drop. You can also observe this with different pitching rates: Pitching Rate Experiment – Tasting | Braukaiser look at pH over pitching rate.
Kai
Its less a factor of the mash or wort pH and more a factor of the yeast. Some yeast produce more acids which results in a more acidic beer. Weizen yeast has a number of factors that are quite different from other yeasts.
I’ve noticed the same thing with wine yeasts. Some are dramatically more acidic than others, even when fermenting in the exact same must.
Interesting, do we know what organic acids are produced in greater abundance? I suppose its citric, malic or lactic. If it were mostly malic I could maybe do malolactic fermentation on my wheat beer like I do for red wine. Given the description of a citric character, I would have to guess citric acid although malic has a pretty tart character as well. Then theres the ferrulic acid possibility which is found at higher levels in wheat, but is decarboxylated by the yeast and is no longer an acid once converted.
I haven’t heard of this before, which ones do you think produce more acid?
In my mead fermentation trials, RC 212 lowered the pH much more than the others. The pH for Cote des Blanc was a little higher, K1V was higher still, and 71B and Premier Cuvee tied for the highest pH.
At the seminar on Berliner Weisse at this summer’s AHA National Convention, the presenter pointed out that the Wyeast 1007 produced a larger pH drop than other yeasts evaluated. Obviously this result is only qualitative and not quantitative, but its a data point for your reference.
To a large extent it is not the secretion of a given acid by yeast but its ability to pump protons (H+) into the surrounding beer during fermentation. This lowers the beer pH and the resulting pH gradient between beer and yeast aids the yeast’s nutrient uptake.
Kai
Maybe but I don’t think you can taste hydrogen ions at a low concentration. Soda pop doesn’t taste tart and its pH is on par with wheat beer. If you are tasting something tart its an organic acid or its salt. So I’m guessing theres something tart produced either by the yeast or from the wheat. Since you don’t expect a lower mash pH just from using wheat, it must be something produced during fermentation.
Now maybe its simply that the pH of wheat beer is what it is, and has nothing to do with an organic acid that is also present and giving the tartness. It would just seem convenient to think that an organic acid at detectable levels, is also contributing to the low pH.
Odd, I’ve never thought of altbier as being acidic or at least not tart. This may suggest that the two (pH and tartness) are not necessarily tied to one another.
I did recently make a wheat beer with WY1056 and it was initially one of the sweetest most lovely American wheat beers I ever made. One keg seemed to get tart after a few weeks of storage (during which time we drank the first keg) but this may have been from a minor infection.